This study aims to explore the application of digital muscle strength testing systems in day care centers and analyze their adaptability and benefits for the elderly population. With the increasing global aging trend, sarcopenia has become a significant health issue, severely impacting the daily functioning and long-term care needs of older adults. Smart sensing technologies provide innovative solutions for long-term care facilities, enabling effective muscle strength and functional movement monitoring in elderly individuals. This study employs a mixed-methods approach, combining quantitative data analysis and qualitative interviews to assess the usability and acceptability of the intelligent testing system in long-term care institutions. The results indicate that the system performs well in muscle strength testing for older adults, with completion rates of 94.87% for the Dorsiflexion Ability and 92.31% for the 3M Gait Test. ANOVA analysis revealed no significant differences between the different stages of testing (3M Gait Test: F = 0.62, p = 0.54; 5 Times Sit-to-Stand Test: F = 0.62, p = 0.54). However, the results show a trend of “improvement at the mid-test and decline at the post-test,” highlighting potential challenges in the long-term implementation of the system in institutions. The qualitative analysis suggests that caregivers have a high level of acceptance of the system but also indicate areas for optimization in adapting the system to the “group nature” of the institution. This study provides valuable insights for optimizing and promoting digital muscle strength testing systems in long-term care facilities.